Transducer devices



Dec. 16, 1958 R. E. GUNTHER 2,864,898

TRANSDUCER DEVICES Filed March 26, 1954 IN V EN TOR.

TRANSDUCER DEVICES Roland E. Gunther, Princeton Junction, N. J.

Application March 26, 1954, Serial No. 419,009

1 Claim. (Cl. 179-108) This invention relates to a device fortransducing modulated electrical signals into corresponding mechanicalvibrations. By imposing the vibrations thereby derived upon a diaphragm,which in its turn can set up air vibrations, the invention becomesusable as a loudspeaker device.

In conventional loudspeakers all of the energy that appears at theoutput in the form of sound has to be supplied by the controlling inputcircuit. This makes it necessary for the control signal to haveundergone a large amount of amplification before reaching theloudspeaker, especially when it is initially derived from such weaksignals as are ordinarily produced by radio frequency circuits in radioreceivers or from phonograph pickups.

It is an object of this invention to provide a means of producing soundfrom an electrical signal with the sound output of an energy levelappreciably higher than that of the electrical signal which carries thecharacteristic, using it only to determine and control the character ofthe sound output.

It is a further object of this invention to provide a means whereby asource of comparatively high level rotational energy can be utilized toproduce vibrational mechanical energy having constantly controlledcharacteristics determined by a modulated electrical signal ofcomparatively small dimensions.

It is also an object of this invention to provide a means of producingorganized sound such as speech or music at high levels of energy, theoutput energy being principally derived from mechanically suppliedenergy, rather than being supplied electrically by the control circuit,as in most present day loudspeakers.

These and other objects, and the manner in which they are achieved willbe elucidated in the following text and the accompanying drawings.

Figure 1 of the drawings represents a side view of a form of theinvention, with a partial cut-away of a frame 6 made to more clearlyshow the manner of construction. Figure 2 shows an end view of the sameform of the invention, a cut-away of the same frame 6 again included.

In Figure 1 and indicated by the numeral 1 is indicated a source ofrotational mechanical energy such as an electric motor. The motor 1drives the input portion of a clutch 2. The clutch 2 is an electricallyengaged type of clutch of the kind known commercially as a magneticpowder clutch, in which electrically produced magnetic fields rigidizethe otherwise fluid medium between the driving and driven portions ofthe clutch. In the drawing there are two leads 10, 11 shown coming fromthe clutch 2, and these represent the input connections to the controlcircuit of the clutch 2. At the rotational mechanical output of theclutch 2 there is illustrated an eccentric means of power take-off inthe form of a crank 3. A link 4 acting similarly to a connecting rod isshown attached at one of its ends to the crank 3, and at its other endto a diaphragm 5, at a central point 12 on the Sttes Patent C) diaphragm5. A portion of the diaphragm 5 only is shown by means of a cut-awaypreviously mentioned in a frame 6, said frame 6 providing a means ofholding the peripheral section of the diaphragm 5. The frame 6 extendsdownwardly in the drawing to join a base 7 upon which said frame 6, themotor 1 and the clutch 2 are mounted. The frame 6 also extends upwardlyand above the diaphragm 5 to provide a support 8 for a spring 9. Thespring 9 is held rigidly by the support 8 and at its other end it actsupon the diaphragm 5, holding said diaphragm 5 elastically at the point12.

The end view of the same form of the invention shown in Figure 2illustrates the same motor 1, the clutch 2 with its leads 10, 11, theattached crank 3, the link 4 to diaphragm 5, a portion of which is madevisible by a cut-away in the frame 6. The spring 9 and its support 8 arealso shown again, as well as the point of attachment 12 on the diaphragm5. Indicated by the numeral 7 is the base.

The device operates as follows. With the motor 1 running, it drives intoclutch 2, and actuation of the clutch 2 by means of an electrical signalfed into the clutch control leads 10, 11 transmits rotational forcethrough the clutch 2 to the crank 3, and this in turn, by means of thelink 4 displaces the portion of the diaphragm 5 in the area of the pointof attachment 12, and at the same time exerts a force upon the spring 9.The spring 9 in its turn exerts an opposing force proportional to theamount of displacement, and when both forces become equal the motion ofthe diaphragm 5 is halted. Any change in the electrical control circuitof the clutch 2 brings about a consequent change in actuation and theamount of force transmitted from the motor 1 through the power train tothe diaphragm. A decrease in the transmitted force allows the spring 9to bring about a return of the diaphragm 5 toward its rest position, andan increase in the power transmitted through the clutch and train bringsabout a further excursion of the diaphragm 5. The displacement of thediaphragm 5 from its rest position at any time is a function of themagnitude of the electrical signal supplied to the clutch 2.

By using an audio modulated electrical signal as the input to thecontrol leads 10, 11 of clutch 2, the resultant motion of the diaphragmwill consist of vibrations at audio frequencies, and the devicefunctions as a loudspeaker. Since the driving power to the device issupplied by the motor 1, and since electric clutches control relativelylarge amounts of power through relatively low energy electrical signals,it follows that this device provides the function of an amplifyingtransducer.

To those skilled in the art a description of a so-called single endeddevice such as that described, immediately suggests the possibility ofcarrying the invention one step further and using two similar units inpush-pull arrangement. In this sort of use, two power sources such aselectric motors are used, one on either side of the diaphragm, eachmotor acting through its power train upon the common diaphragm. The twoelectric clutches are, in this case, fed by the usual out of phasesignals that make a push-pull circuit operable. In this case, also, thespring 9 in the form of the device shown in the drawings would not beneeded.

The replacement of the spring by an opposing motor and clutcharrangement provides a means of subjecting the diaphragm to returnimpulses that are not, as in the case of spring motivated return, afunction of the preceding displacing impulse. Such a push-pull arrangement also makes it possible to eliminate spurious responses otherwiseintroduced by the spring at its resonant frequency period and atharmonics thereof.

I claim:

In a device for transducing electrical wave forms into Patented Dec. 16,1958 corresponding sound wave forms the combination of a source ofrotational mechanical energy, a magneticfiuid clutch, said magneticfluid clutch conventionally comprising a rotational mechanical input anda rotational mechanical :output as well astan:electricalccontcolycircuit; saidsource of rotational:mechanicaL-energy applying to said rotational mechanical .input,ofiasaid.magnetic fluid clutch; an CCCCHtI'iCZJPOWCI'J take-:ofiumeans,tsaid eccentric means applying .lZOvSflid "rotational-mechanical outputof said magnetic fluid clutch; :awdiaphragm; a

frame, said frame peripherallycmounting saidmdiaphragm; a mechanicallinking means, said1 mechanical linking means applying betweensaideccntrimpoweriake ofi and said diaphragm, and said::meel1anical linkingmeans as!) disposed with respectsto'said: diaphragmto applyrlinearmotion derivable from said eccentric :means: to said 1 diaphragm in adirection essentially perpendicular to said diaphragmra spring, one endof said spring rigidly held by said frame, the other end of said springapplying elastically to said diaphragm in linear opposition to saidmotion derivable from said linking means; and said electrical wave formsto be transduced into sound being applicable to said electrical controlcircuit of said magnetic fluid clutch.

References;Cited in the Lfileof .this patent UN1'1IED;STATES *PATENTS1,533957 ,lRahbeket a1. Apr..14, 1924 1,702,935 Edison Feb. 19, 19292,644,427 Sedgfield etal. July 7, 1953 2,661,825 Winslow Dec. 8, 1953

